Wristband lock



J. PFISTERER WRISTBAND LOCK July 1, 1952 Filed July l5, 1949 Patented July 1, 1952 UNITED STATES PATENT GFFICE vApplication July 15, 1949, Serial No. 104,935 v4In- Germany October 1, 1948 l 2 Claims. 1

This invention relates to clasps for 'wrist watch bands and the like, and more particularly to clasps of the folding extension type.

It is an important objectof the present invention to provide for a Wrist banda clasp of this type of which the foldable parts Will intheir folded condition become locked more securely the more the band is tensioned during regular wear on the Wrist.

It is another important o-bject of the present invention to provide for a Wrist band a clasp of this type of which the foldable parts may, despite their secure lock during regular Wear of the band on the wrist, be locked and unlocked by the wearer with exceptional ease.

It is a more specific object of the present invention to provide for a wrist band a clasp of this type of which the foldable parts may in their folded condition be locked and unlocked on extremely simple manipulation of the same by the wearer and onthe exertion by the latter of an unusually light force which is only `a small fraction of the force with which the parts are held locked in their folded `condition during regular wear of the band.

It is also among the more important objects of `the present invention to provide a'clasp of this type which is of very simple-construction, great strength and pleasing appearance, and which readily lends itself to efficient and inexpensive mass production. l

The above and other objects, features and advantages of the present invention Will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

Fig. 1 is an enlarged fragmentary elevational View of a wrist band having a clasp which embodies the present invention;

Fig. 2 is a section taken on the line V2--2 of Fig. 1;

Fig. 3 is a section 'similar Vto Fig. 2, butshowing the parts of the clasp in'a different condition;

Fig. 4 is an enlarged `fragmentary section through the band, showing the clasp thereof in unfolded condition; and

Fig. 5 is an enlarged fragmentary elevational view of the band as viewed in the direction of the arrow 5 in Fig. 4.

Referring to the drawings, the reference numeral l0 designates a Wrist band which may be used for Wearing a wrist watch. The wrist band ID may be of any suitable type, being shown, in the present instance, as comprising a plurality of ornamental links l2 Yconveniently joined end to end by pivot pins I4 which may be received by intertted, conveniently rolled hinge ends I6 and I8 of adjacent links l2. The links l2 may be made of any suitablematerial such as precious or non-precious metal and may assume any desired shape.

The wrist band l0 is, for its closure, provided with a clasp 20 of the folding `extension type, which comprises the usual back-plate 22, and fold-over plates 24 which are pivotally connected by pins 25 with the opposite ends of the-back plate 22. Conveniently, the pivotally connected ends of the back plate 22 and fold-over plates 24 are rolled to provide hinge ends 28 and 30 in which the pins 26 may extend (Figs. 4 and `5). The other ends of the fold-over plates `24 are connected by pivotv pins 32 with the adjacent end links l2 of the band l0. To this end, each foldover plate 24 and associated link l2 may conveniently be provided with rolled hinge ends 34 and 36 in which a pivot pin V32 extends: (Figs. 4 and 5).

Further pivoted at 38 on one of the pins 32 is a lock member 40 which, like the plates 22 and 24 of the clasp, is preferably made of precious or non-precious metal. The lock member 40 may be of the form shown, `and is provided with a hook-like portion 42 and a handle end44.

In applying the band I0, `the parts 22 and 24 of the clasp 20 are unfolded (Fig. 4) for ready passage of the band over the `hand and onto the Wrist of the wearer. The band I0 is thereupon closed on the wearers wrist by folding the plates 24 of the clasp against the back plate 22 thereof and turning the` lock member 40 into the closed position shown in Figs. 1 and 2, in which its hook portion 42 is interengaged with the hinge end 34 of the adjacent fold-over plate 124 which forms a shoulder element that is inclined downwardly toward the latter .fold-over plat-.e 24 and inwardly toward the opposite fold-over plate 24. The lock member 40 is so arranged that only a very light closing force is required in order to snap its hook portionv42 over and behind the hinge end 34 of Ythe adjacentfold-over plate 24, provided both fold-over plates 24 are in engagement, or near engagement, with the back plate 22 (Fig. 2). Since the fold-over plates 24 are in stinctively forced by the wearer into engagement, or near engagement, with the back plate 22 of the clasp in order to hold the band I on the Wrist prior to and during the closure of the lock member 401, it stands to reason that closure of the latter will invariably meet with little resistance and require a very light closing force.`

When the wearers hand releases the band I after closure of the lock member 40, the band, if of the correct size to t somewhat snugly on the wearers wrist for best results, will be more or less tensioned by the wrist during regular wear thereon. This normal tension in the band l0 during wear tends to open the clasp 20 by unfolding the plates 24 (Fig. 3), but the unfolding tendencies of the latter are safely resisted by the closed lock member 40 by virtue of the interengagement 0f its hooked portion 42 with the hinge end 34 of the adjacent plate 2 4. More particularly, the action of the lock member 40 is such that the relatively loose interlock of its hooked portion 42 with the hinge end 34 of the adjacentV fold-over plate 24 at the time of the closure of the lock member becomes rmer the greater the forces are that tend to unfold the folded plates 24 in consequence of the tension in the band l0 from the wearers wrist. Hence, it is this feature of the lock member 40 which securely and reliably holds the parts 22 and 24 of the clasp I0 in their folded condition (Fig. 3) when the band I0 is subjected to ordinary or even extraordinary tension from the wearers wrist. Thus, the lock member 40 will hold the clasp 20 securely closed so long as the fold-over plates 24 are not forced inwardly into engagement, or near engagement, with the back plate 22 0f the clasp and the lock member 40 is not simultaneously turned deliberately from its closed position. Ordinarily, the fold-over plates 24 are, in their folded condition, forced away from the back plate 22 to the maximum extent permitted by the closed lock element 40 when the band I0 is worn, and it will usually require deliberate inward manipulation by the wearer of the fold-over plates 24 into engagement, or near engagement, with the back plate 22 in order to condition the lock member 49 for its opening with the same ease with which it may be closed on properly applying it to the wrist, as described. If during ordinary Wear of the band I0 the folded plates 24 should accidentally or unintentionally beforced from their normal disposition (Fig. 3) into engagement, or near engagement, with the back plate 22 (Fig. 2), it would still require simultaneous accidental opening of the lock member 40 in order to open the band I0 to its fully expanded state. That both of these contingencies should occur unintentionally and simultaneously is highly unlikely, wherefore the instant clasp is particularly safe against accidental opening.

Thus, the instant clasp is highly advantageous from several points of view. It is, as just mentioned, particularly safe against accidental opening. Furthermore, the clasp requires no skill and hardly any eifort on the part of the wearer in order to open and close it when desired, yet it will during regular wear remain closed even under extraordinary tension of the band on which it is provided. Also, the construction of the instant clasp is extremely simple, requiring only a minumum number of inexpensive parts which may be structurally very strong without being bulky,` and which may be formed so as to lend to the finished clasp a pleasing appearance. Last but not least, the simple parts, of which the instant clasp consists,

may readily be assembled without requiring 7 4 much skill, Wherefore, the instant clasp readily lends itself to eicient and inexpensive mass production.

While I have shown and described a preferred embodiment of my invention, it will be under? stood that various changes may be made in the present invention without departing from the underlying idea or principles of the invention within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A folding extension type clasp for use with a wrist band, comprising three end-to-end pivoted rigid members of which the intermediate member is longer than either of the outer members and the latter are turnable into superposed relation with said intermediate member in which their outer faces confront the outer face of the latter member, an inclined shoulder element projecting outwardly from the inner face of one 0f said outer members remote from the pivoted end 0f the latter, said shoulder element being inclined downwardly towards said one outer member and inwardly towards said other outer member, a lock element pivoted with one end 0n the other outer member remotely from the pivoted end of the latter and having a hooklike opposite end complementary to said shoulder element and snappable over said inclined shoulder element into releasably interlocked relation therewith on turning said lock element against said one outer member in the superposed relation 0f said outer members on said intermediate member, whereby said superposed rigid members may be locked with ease and become locked more securely as the wrist band is tensioned, and wrist band attachment provisions on said members, respectively, remote from their pivoted ends, said lock element being of slightly resilient material whereby said hook end of said lock element is snappable with a very light force over said shoulder element in the superposed relation of said members.

2. A folding extension type clasp as set forth in claim 1, in which said shoulder element is formed by a cylindrical centrally positioned hinge portion on the end of said one member opposite its pivoted end, said hinge portion being adapted for pivotal connection of said one member with one end of a wrist band.

JULIUSA PFISTE-RER.

REFERENCES CITED The following references are of record in the Germany 'Nov. 4,1935 

